Mobile self propelled bridge units



1951 J. GILLOIS ET AL MOBILE SELF PROPEILLED BRIDGE UNITS 8 Sheets-Sheet1 Filed June 3, 1957 INVENTOPS Jean GILLO/S Hermann Walter GEHLEN Nov.28, 1961 J. GILLOIS ETAL 3,010,128

MOBILE SELF PROPELLED BRIDGE UNITS Filed June 3, 1957 8 Sheets-Sheet 2INVENTOR-S "I l Jean G/LLO/S Hermann Wall-er GEHLEN Nov. 28, 1961 J.GILLOIS ET AL 3,010,128

MOBILE SELF PROPELLED BRIDGE UNITS Filed June 3, 1957 8 Sheets-Sheet 3INVEN 1'01? 8 Jean GILL 0/5 Herm ann Walt-er GEHLE N Aq-av 8Sheets-Sheet 4 J. GlLLOlS ETAL MOBILE SELF PROPELLED BRIDGE UNITS Nov.28, 1961 Filed June 3, 1957 Nov. 28, 1961 J. GILLOIS ETAL MOBILE SELFPROPELLED BRIDGE nuns 8 Sheets-Sheet 5 Filed June 3, 1957 Nov. 28, 1961J. GILLOIS ETAL MOBILE SELF PROPELLED BRIDGE UNITS Filed June 3, 1957 8Sheets-Sheet 6 INVEN TO 7- S Jean GIL L 0 I6 Hermann Wall-er GEH L ENNov. 28, 1961 Filed June 3, 1957 J. GlLLOlS ET AL 3,010,128

MOBILE SELF PROPELLED BRIDGE nuns 8 Sheets-Sheet 7IIIIIIIIIIIIIIIIIIIIIIIIII'IIIIIIIIllIIIIIllI/I Evil/1111111111111!!!fie l IIIIIIIIIIIIIIIIIIIIIIII.

VIIIIIIIIIIIIIIII IN VEN TO 7-?8 Jean G/LLO/S Hermann Valfer GEHL ENayM/W Nov. 28, 1961 J. GILLOIS ETAL MOBILE SELF PROPELLED BRIDGE UNITS 8Sheets-Sheet 8 Filed June 3, 1957 IN VEN r0 1-?8 m 61.. n mm UnitedStates i atenr MOBILE SELF PROPELLED BRIDGE UNITS Jean Gillois, Rastatt,Germany, and Hermann Walter Gehlen, 6t) Pirmasenser Strasse,Kaisersiautern, Main,

Germany, assignors, by mesne assignments, to Hermann Waiter Gehlen,Kaisersiautern, Plain, Germany Filed June 3, 1?57, Ser. No. $36,262Claims priority, application Germany dune 4, 1956 7 Claims. (Cl. 14-1)The present invention relates to mobile self-propelled bridge units.

Numerous proposals are already known for the rapid installation orassembly or bridge in situ. In the case of the majority of mobileself-propelled bridges or bridge units these proposals are restricted tolight structures of scissor-like form and which have comparatively smallspans for use by light loads. While mobile the scissorlike structuresare closed, but on the site of their operation they are opened over theobstacle to be surmounted.

Locomotive bridges are also known wherein a finished steelsuperstructure is mounted by means of rolling segments in the centre oftwo floating track vehicles and is provided with devices for thecoupling of other steel superstructures, while the first and the lastunit of a bridge of this kind has extensible ramps.

The object of the present invention is to provide a mobileself-propelled and rapidly erectile bridge for use on land, which isconstructed with the least possible amount of material yet enables steepprecipices, comparatively large uneven stretches of ground, cuttings,smaller rivers, brooks and the like to be rendered negotiable tovehicles or to be otherwise bridged.

This object is achieved in accordance with the present invention by amobile self-propelled bridge unit and having a main bridge componentconsisting of two main girders interconnected or spanned by a roadway,and at either or both ends of which component ramps, preferably ofdifferent lengths, are hinged so as to be flapped over on to the deck ofthe bridge during travel to and from sites of use and to extend beyondthe ends of the bridge during use.

Conveniently there is inserted between the lower boom or girder of eachramp and the main bridge component a hydraulically, pneumatically,mechanically or electrically actuated system of rods, by means of whichthe ramps are swung out into the operative position and can either bothbe fixed at predetermined inclines to the roadway or in the samedirection as the roadway so that the main bridge component and itshinged ramps form a rigid composite bridge unit.

It has proved to be particularly advisable to provide additional lockingof the ramps and the main component in their trafiic accommodatingposition, by means of bolts engaging in eyes of butt straps forrelieving the actuating rods of the ramps of unnecessary load. Thelocking bolts may be actuated mechanically or hydraulically from thedrivers cabin for various positions of the ramp. The advantage of thisconstruction is that the strength of the actuating rods for the rampsshould be suficient for ensuring the folding operation of the rampsleaving the load created by trafiic on the bridge to be taken care of bythe bolts.

In the case of a bridge unit having ramps movabl fitted at both ends, itis possible to utilise two drives in displacing each or" the ramps, thecenters of rotation of which are displaced relative to each other sothat upon the moving of a ramp into a zero position with the rampstanding perpendicularly, one drive always continues to work and movesthe ramp out of the zero position.

ere each of the ramps consists of two relatively displaceable parts, thesecond part may be moved in the same manner by means of two drives.

ice

The chassis and/or the axles of the unit may be retractable andextensible.

'In order to facilitate and simplify conveyance of the bridge unit innarrow streets and to render possible the loading of a bridge unit on torailway trucks with respect to the above-described clearances, thebridge unit may be relatively narrow but with laterally extensibleattachments for widening the roadway of the unit when in use.

The bridge unit may be so constructed that it is adapted to float, i.e.in the manner of a pontoon. By this means it is possible to movevehicles across a river and to assemble them on the opposite bankthereof without having to use a bridge structure.

Further features of the invention and details of the advantages achievedthereby will be apparent from the following description'of embodimentsof bridge units illustrated in the accompanying drawings in which:

FIGURES 1 and 2 illustrate in side and front elevation respectively oneform of bridge unit according to the invention.

FIGURES 3-7 show diagrams of difierent possible uses of the bridge unit.

FIGURES 8, 8a and 9 show a bridge unit having bipartite ramps in theoperative position and in the travelling position.

FIGURES 10 and 11 aredetails illustrating the locking of the rampstogether with the main bridge component.

FIG. 12 is a longitudinal section of the vehicle shown in FIG. 9 havinga front and a rear ramp, each of which is made of two parts.

FIG. 13 is a side view of the vehicle shown in FIG. 12 showing differentpositions of the larger of the two ramps.

FIGURES l4 and 15 show, in plan and in cross section, an attachedportion hooked to the main bridge unit for the purpose of widening theunit driving use.

FIGURES 16 and 17 show in cross section an attachment, consisting ofpivotable brackets and a drag sheet, respectively in the inoperative andwithdrawn positions.

FIGURES 18 and 18a show a bridge constructed of several units withunder-tensioning means for connected units.

FIGURES l and 2 diagrammatically represent a bridge unit in its simplestform. The main body of the unit is shown at I and comprises a pair ofmain girders 3'7 and an interconnecting roadway 36. A relatively longramp 2 and a shorter ramp 3 are linked to the main body 1 at oppositeends thereof. The vehicle has its own drive 4 and retractable wheels 5.

When in transit, the ramps 2, 3 are folded over the road surface or deckof the main bridge body 1. The vehicle is driven to the uneven stretchof land, the brook, the steep precipice or the like site of operation,whereupon the two ramps are unfolded so as to project beyond the ends ofthe main body. The movement of the ramps may be achieved hydraulically,pneumatically, mechanically orelectrically, and the drive for this issuch that a folding angle of about 200 may be obtained.

In the embodiment shown in FIGURE 1, the movement of the ramps iseffected by hydraulically controlled rods 6. These are so constructedthat the ramps may be fixed at any desired incline relatively to theroadway of the bridge.

FIGURES 3-7 are illustrative of various possible uses of a mobile bridgeunit having two approach ramps at its opposite ends. The bridge unitfirst approaches the obstacle to be bridged, which in FIGURES 3 and 4 isa ditch A, near enough for the unit to project partly over the ditch.The front and rear axles are then retracted and the unit deposited onthe ground. If the unit is intended to project as far as possible at thefront, it is possible previously to unfold the ramp 3 at the back and tomount a counter weight thereon, for instance by using ballast or byanchoring the end of the ramp 3 or loading it with another heavyvehicle, such as a tank 8 (FIGURE 5). The forces to be absorbed by theramp are transmitted through the hydraulically controlled rods 6 to thebody of the bridge. The longer ramp 2 is then unfolded (FIGURE 6).

Rather small rivers of about 20 metres width may be bridged for exampleby driving the mobile unit into the river down the sloping bank thereof.Since the unit can float, this should be possible without difiiculty.After the unit has been deposited on the bed of the river the two rampsare unfolded with the ends of these ramps reaching the sloping banks. The unit can then be raised with the hydraulic system of the ramps sothat a bridge is formed between the two banks.

FIGURE 7 shows the use of a bridge unit for overcoming an obstacle inthe form of a steep wall. For this purpose the unit is first broughtinto the position illustrated by broken lines. Then the centre portionwith the two ramps is brought into an extended position by actuating therod 6 between the large ramp 2 and the centre portion.

In order to relieve the rods 6 in the traflic position, the ramps andthe bridge unit may, after they have been brought into the finalposition, be hydraulically locked together. This locking arrangement canbe actuated from the drivers cabin for various positions of the ramp. Itconsists of butt straps 13 with eyes 14 arranged on the lower boom andwhich are engaged by butt straps 15 mounted on the ramp and having holes16 (FIGURES 1 and 311). Locking is effected with the aid of a bolt 17mechanically or hydraulically snapped into the holes 14, 16 after theunfolding of the ramp. The rods 6 require to be of suflicient strengthto ensure folding of the ramps and the raising of the bridge girder(FIGURE 7) where required while the locking mechanism, takes care of theforces arising from any loading of the bridge, such as by the passage ofvehicles across it.

A development of the travelling bridge unit is illustrated in theembodiment shown in FIGURES 8 and 9. In this form of construction eachof the two ramps 2 and 3 is divided into two parts, those of the lengerramp being shown at 2a and 2b and those of the shorter ramp at 3a and319 respectively. For use in situ, the ramps are first unfolded togetherand then singly. The advantage of this arrangement is that morefavourable conditions are obtained, particularly in use of the unit. Inthe case of a unit length of 11 metres for example, the ramp 2 insteadof being say metres long may, in the embodiment shown in FIGURES 8 and9, be formed of bipartite elements of eight and seven metres lengthmaking a total of metres when extended. Similarly the ramp 3 instead ofbeing 4-5 metres in length could, when in two parts, have a length of5+6 metres, i.e. 11 metres in all. In the result, longer spans may bebridged by the unit of FIGURES 8 and 9. The unfolding of the two rampmembers may be effected mechanically or hydraulically.

The bridge unit illustrated in FIG. 12 is constructed essentially in thesame manner as the bridge units of FIGURES l-ll. For better support andfor an improved distribution of forces, particularly when acomparatively lengthy wheel span is required, a pair of disc wheels 10as shown in FIGS. 12, 18 and 1811, which may be raised and lowered atwill, are provided on both longitudinal sides approximately in themiddle of the vehicle. In FIG. 12 these wheels are merely indicated onthe remote side of the vehicle and in interrupted lines to provide forclearness.

The front and rear ends of the vehicle in accordance with FIGS. 9, 12and 13 is provided with hinge means 7 to which ramp portions 2a, 2b, 3aand 3b are pivotally secured. The forward and topmost ramp members orgirders 2b and 3b are secured at their lower girder portions to the rampportions 2a and 30, respectively, by means of shafts 52. The lateralattachment members 21.

for widening the roadway are stored on and securely fastened to the rampportion 31) during street travel.

The propulsion of the vehicle is effected by the motor means 53 whichtransmits the driving power to the rear axle 33 and if desired also tothe front axle 39. The steering takes place from the drivers cab 40 byWay of steering column 41 and the shafts 43 which are passed over theforward wheel housing 4-2, and connected to the steering gear of theaxle 39.

The wheel assemblies 44 can be retracted into the completely closedwheel housings or chambers 42. Axles 38 and 39 are connected for thispurpose by means of springs 45 to pivotable frames 46. Frames 46 in turnare pivotally mounted at joints 47 on the vehicle body 1. For streettravel the free ends of the pivotable frames 46 are securely locked bymeans of hydraulic or other mechanical latches 48 on the body of thevehicle. It is thus possible to let out or retract the entire drivingassembly, upon release of the latch members 48, with the hydraulictwo-way operating cylinders 49.

It will be apparent from FIG. 12 that it is possible by means ofhydraulic cylinder 49 to extend the wheel assemblies 44 sufficiently farto permit tire changing, thus eliminating the necessity of specialrecesses in the walls of the wheel chambers. Complete retracting of thewheel assemblies removes any tratfic loads from the axles when thevehicle is deployed as a bridge span.

The hydraulic cylinders 6 and 6"are pivotally mounted on the vehiclebody while the piston rods thereof are linked to the ramp halves 2a and2b and 3a and 3b. The hydraulic cylinders 6' are each connected at oneend to the ramps and their piston rods are pivotally connected tospecial pivot arms 50 which in turn are rotatably journalled on the ramppivot rods 52 for movement independently of the ramp. The pressure fluidfor moving the ramp cylinders is supplied by the fluid pump 51 which ismounted on a flanged portion of the engine or prime mover '37. Thecontrol of the ramp movement is effected by a hydraulic control providedin the drivers cab 40.

The swinging operation of the ramps 2 and 3 is the same for both rampsand is described hereinafter with reference to ramp 2. The vehicle instreet travel condition is driven into close proximity of the gap orrecession in the terrain and the wheel assemblies are completelyretracted to engage the bottom of the vehicle body with the ground. Thetwo ramp sections 2a and 2b are swung out in folded condition by meansof the hydraulic cylinder 6 until the axis of the cylinder is positionedshortly ahead of the center point of the hinge '7 of the lowerconnection of the ramp portion 2a with the vehicle body, which is thedead center position shown in full lines in FIG. 13.

Since ramp cylinder 6 now has no leverage to apply force to the hinge 7,further swinging of the ramp cannot be effected by means of thiscylinder alone. Therefore the forward ramp portion 2b is swung forwardlyby the hydraulic operating cylinder 6' to an extent of about -90, asillustrated in FIG. 12. As a result the center of gravity of the tworamp halves 2a and 2b is shifted forwardly so that the entire rampswings forward under its own power. To prevent the ramp from droppingfreely the ramp cylinder 6 acts as a brake during this phase of themovement. For this purpose an over-pressure valve is connected to thecylinder 6 which regulates the maximum pressure and therefore thebraking moment. Continued swinging movement of the forward ramp portion2b by means of the hydraulic cylinder 6' and continued yielding ofcylinder 6 results in the completely stretched position of the ramp overthe gap in the terrain. Upon extending the rear ramp 3:: and 3b in thesame manner it is now possible for heavy caterpillar and wheel vehiclesto travel over the rapid deploying bridge.

Cylinder 6 of the large ramp 2a, 2b establishes a rigid connectionbetween the ramps and the body of the vehicle after locking of thehydraulic control. It is possible to construct the cylinder also in amanner that it remains movable so that the connection of the ramps withthe vehicle body is movable. It is also possible to supply the hydraulicfluid to the other side of the piston of cylinder 6 thereby obtainingupward pressure against the vehicle body to bridge steep slopes as shownin FIGS. 7 and 8.

The returning or retracting of the large ramp 2a and 2b takes place in asequence which is opposite to the outward swinging operation, except forthe swinging across the dead center position where the forward rampportion 212 remains in the stretched position. In this manner the centerof gravity of theramp is shifted rearwardly so that the return swingingmovement is possible.

By coupling together the various embodiments of bridge units, landirregularities caused by streams, small rivers and the like can bebridged in a very short time and practically without any appreciableassembly ditriculties.

FIGURES 14l7 show details of construction of attachments for wideningthe roadway of a mobile bridge unit.

In the embodiment shown in FIGURES 14 and 15 the component 1 of a mobilebridge unit having its own drive, has at the sides of its deck orroadway recesses 18 which are bridged in the outermost corner of theunit by a short round iron bar 19 welded, or secured in any othermanner, to the wall of the bridge unit. Attachments 21 for widening theroadway are hooked to the bar 19 by means of hooks 20. These attachments21 are supported by their lower portion engaging directly against thewall of the bridge unit or with the insertion of a plate or butt strap22. Each attachment is constructed as a hollow girder and has anupstanding part 23 constituting a scraping edge.

In the embodiment shown in FIGURES 16 and 17, a number of verticallydisposed bolts 25 are arranged along the side or longitudinal Walls 24of the bridge component 1 to operate as pivots for brackets 26. A dragsheet 27 is secured by means of a bolt 28, to the free end of thebrackets remote from the pivots 2 5. The drag sheet is kinked in crosssection at 2? over the place of its attachment to the free end of thebracket 26. By this kink 29 the drag sheet 27 is disposed on thehorizontal flange 30 of an angle iron 31 extending axially of the bridgecomponent, and is thereby mounted slightly resiliently. Similarly, thebolt 28 holding the drag sheet is resiliently secured in itslongitudinal axis by a helically wound spring 32. In the withdrawnposition, the drag sheet, with its free longitudinal edge, is disposedon a butt strap 33 se cured to the bridge unit so that the inner edge ofthe drag sheet lies in the plane of the road surface of the main bridgecomponent 1.

For swinging in the unfolded brackets together with the drag sheets,these are raised to the roadway of the bridge by means of a hook. Thebrackets can then be swung about the pivots 295 into recesses in theupper part of the bridge. The free end of the drag sheet is providedwith a projection 34 which engages when the brackets are in-theinoperative position, in an aperture in'the roadway of the main portionof the bridge and retains the brackets and the drag sheet in theinoperative condition. The outside of the angle iron 31 is provided witha scraping edge 35.

In order to achieve the greatest possible supporting length, coupledbridge components may be under-or overtensioned, for example asillustrated in FIGS. 18 and 18a. Cables 12. controlled by a winch areprovided for this purpose. By suitably guiding the cables, trafiic loadsmay be absorbed in the case of under-tensioning and, in the case ofover-tensioning, favourable efiects are achieved when the front lengthis extended unsupported. In the case of under-tensioning, the tensioncables 12 (FIGS. 18 and 18a) are guided over a pair of disc wheelsprojecting beyond the base of the unit. For over-tensioning purposes, anon-illustrated system of rods actuated hydraulically, mechanically orin any other manner, is provided with a pulley for guiding the cable.

We claim:

l. A mobile self-propelled unitary structure defining a bridge unit inthe form of a floating body having a main body comprising generallyparallel side members, an interconnecting roadway extending intermediatesaid side members, a prime mover, actuating means associated with saidprime mover and retractable wheels operatively associated with saidactuating means and disposed generally within the confines of said sidemembers, said body being provided at least at one end thereof with rigidconnecting means in the form of supporting hinge means or the like, aramp having corresponding hinge means on that part thereof which islowermost for the position of rest of said ramp on said main body, saidcorresponding hinge means being connected to said supporting hingemeans, and power actuated rods or the like associated with saidactuating means disposed intermediate said main body and a part of saidramp proximate said hinge means, whereby said ramp is angularlydisplaceable into fixed operative positions at predetermined inclinesendwise of said roadway to constitute a continuous track defined by saidroadway and said ramp, said body and ramp including interengaging strapsor thet like having apertures, and bolts operative to extend throughsaid apertures, thereby locking said ramp in adjusted position relativeto said body and relieveing the actuating rods.

2. A mobile self-propelled unitary structure defining a bridge unit inthe form of a floating body having a main body comprising generallyparallel side members, an interconnecting roadway extending intermediatesaid side members, a prime mover, actuating means associated with saidprime mover and retractable wheels operatively associated with saidactuating means and disposed generally within the confines of said sidemembers, said body being provided at least at one end thereof with rigidconnecting means in the form of supporting hinge means or the like, aramp having corresponding hinge means on that part thereof which islowermost for the position of rest of said ramp on said main body, saidcorresponding hinge means being connected to said supporting hingemeans, and power actuated rods or the like associated with saidactuating means disposed intermediate said main body and a part of saidramp proximate said hinge means, whereby said ramp is angularlydisplaceable into fixed operative positions at predetermined inclinesendwise of said roadway to constitute a continuous track defined by saidroadway and said ramp, said body and ramp including interengaging strapsor the like having apertures, and bolts operative to extend through saidapertures, thereby looking said ramp in adjusted position relative tosaid body and relieving the actuating rods, and automatic operatingmeans for said bolts associated with said actuating means.

3. A mobile self-propelled unitary structure defining a bridge unit inthe form of a floating body having a main body defined by generallyparallel side members, an interconnecting roadway extending intermediatesaid side members, a prime mover, actuating means associated with saidprime mover, and retractable wheels operatively associated with saidactuating means and disposed generally within the confines of said sidemembers, said body being provided at least at one end thereof with rigidconnecting means in the form of supporting hinge means or the like, aramp having corresponding hinge means on that part thereof which islowermost for the position of,rest of said ramp on said main body, saidcorresponding hinge means being connected to said supporting hingemeans, and power actuated rods or the like associated with saidactuating means disposed intermediate said main body "and :a part ofsaid ramp proximate said hinge means, whereby said ramp is angularlydisplaceable into fixed operative positions at predetermined inclinesendwise of said roadway to constitute a continuous track defined by saidroadway and said ramip, said ramp being defined by a lower and an upperboom, said corresponding hinge means being provided on said lower boomand said rods of said power actuated means being connected to that partof said lower boom which is uppermost for the position of rest of saidramp on said roadway.

4. A mobile self-propelled unitary structure defining a bridge unit inthe form of a floating body having a main body comprising generallyparallel side members, an interconnecting roadway extending intermediatesaid side members, a prime mover, actuating means associated with saidprime mover and retractable wheels operatively associated with saidactuating means and disposed generally within the confines of said sidemembers, said body being provided at least at one end thereof with rigidconnecting means in the form of supporting hinge means or the like, aramp having corresponding hinge means on that part thereof which islowermost for the position of rest of said ramp on said main body, saidcorresponding hinge means being connected to said supporting hingemeans, and power actuated rods or the like associated with saidactuating means disposed intermediate said main body and a part of saidramp proximate said hinge means, whereby said ramp is angularlydisplaceable into fixed operative positions at predetermined inclinesendwise of said roadway to constitute a continuous track defined by-saidroadway and said ramp, said ramp being defined by a lower and an upperboom, said corresponding hinge means being provided on said lower boomand said rods of said power actuated means being connected to that partof said lower boom which is uppermost for the position of rest of saidramp on said roadway, said power actuated means comprising said rods andfluid operated pistons, and each of said parts of said ramp having twodrives, the center of rotation of each of said drives being displaced ina manner that in operation, upon reaching substantially vertical zeroposition, one of said drives continues to operate to move the ramp outof said zero position.

5. A mobile self-propelled unitary structure defining a bridge unit inthe form of a fioating body having a main body comprising generallyparallel side members, an interconnecting roadway extending intermediatesaid side members, a prime mover, actuating means associated with saidprime mover and retractable wheels operatively associated with saidactuating means and disposed generally within the confines of said sidemembers, said body being provided at least at one end thereof with rigidconnecting means in the form of supporting hinge means or the like, aramp having corresponding hinge means on that part thereof which islowermost for the position of rest of said ramp on said main body, saidcorresponding hinge means being connected to said supporting hingemeans, and power actuated rods or the like associated with saidactuating means disposed intermediate said main body and a part ofsaid'ramp proximate said hinge means, whereby said ramp is angularlydisplaceable into fixed operative positions at predetermined inclinesendwise of said roadway to constitute a continuous track defined by saidroadway and said ramp, said unit having recesses along the upper outerlongitudinal edges bridged by round iron bar members and elongatedattachments having hook conformations in engagement with said iron barmembers and presenting upper substantially horizontal surfaces extendinglaterally of said roadway, thereby widening said roadway.

6. A mobile self-propelled unitary structure defining a bridge unit inthe form of a floating body having a main body comprising generallyparallel side members, an interconnecting roadway extending intermediatesaid side members, a prime mover, actuating means associated with saidprime mover and retractable wheels operatively associated with saidactuating means and disposed generally within the confines of said sidemembers, said body being provided at least at one end thereof with rigidconnecting means in the form of supporting hinge means or the like, aramp having corresponding hinge means on that part thereof which islowermost for the position of rest of said ramp on said main body, saidcorresponding hinge means being connected to said supporting hingemeans, and power actuated rods or the like associated with saidactuating means disposed intermediate said main body and a part of saidramp proximate said hinge means, whereby said ramp is angularlydisplaceable into fixed operative positions at predetermined inclinesendwise or" said roadway to constitute a continuous track defined bysaid roadway and said ramp, said unit having recesses along the upperouter longitudinal edges bridged by round iron bar members and elongatedattachments having hook conformations in engagement with said iron barmembers and presenting upper substantially horizontal surfaces extendinglaterally of said roadway, thereby widening said roadway, and havingouter ends raised relative to said roadway to form a scraping edge.

7. A mobile self-propelled unitary structure defining a bridge unit inthe form of a floating body having a main body comprising generallyparallel side members, an interconnecting roadway extending intermediatesaid side members, a prime mover, actuating means associated with saidprime mover and retractable wheels operatively associated with saidactuating means and disposed generally within the confines of said sidemembers, said body being provided at least at one end thereof with rigidconnecting means in the form of supporting hinge means or the like, aramp having corresponding hinge means on that part thereof which islowermost for the position of rest of said ramp on said main body, saidcorresponding hinge means being connected to said supporting hingemeans, and power actuated rods or the like associated with saidactuating means disposed intermediate said main body and a part of saidramp proximate said hinge means, whereby said ramp is angularlydisplaceable into fixed operative positions at predetermined inclinesendwise of said roadway to constitute a continuous track defined by saidroadway and said ramp, said unit being provided with a plurality ofperpendicularly disposed pivot bolts secured to the longitudinal outersides thereof and a plurality of brackets, one mounted on each bolt,said brackets being movable about said bolts and having each a fasteningbelt at the free end thereof and drag sheets mounted endwise of saidbrackets by means of said bolts and being movable outwardly with saidbrackets to widen said roadway.

References Cited in the file of this patent UNITED STATES PATENTS1,289,880 Newman Dec. 31, 1918 1,447,893 Roy Mar. 6, 1923 2,282,519Holmes May 12, 194-2 2,449,829 Agren Sept. 21, 1948 2,543,054- PeterFeb. 27, 1951 2,556,175 Frost m June 12, 1951 2,711,803 Hurst June 28,1955 FOREIGN PATENTS 785,137 France May .13, 1935 1,112,888 France Nov.23, 1955

